P2.76 Predictable structures in idealized steady state hurricanes

Thursday, 13 May 2010
Arizona Ballroom 7 (JW MArriott Starr Pass Resort)
Bonnie R. Brown, University of Washington, Seattle, WA; and G. J. Hakim

While aspects of hurricane forecasts, such as track, having improved dramatically over many years, accurate predictions of intensity and storm structure, even on short time scales, have proved elusive and still presents a major challenge to dynamical forecasts. While several factors likely contribute to this problem, here we focus on the predictable aspects of storms without the complications inherent to real storms, such as data assimilation and inhomogeneous sampling. We propose that to better understand and predict the evolution of tropical cyclone intensity and structure, a better understanding is required of the dynamics of internal storm structures that hold the most predictable information, such as whether these structures are primarily axisymmetric or asymmetric. To address this problem, we have designed a framework that avoids complicating aspects of real storms in favor of a statistical analysis of a simulated, steady, idealized tropical cyclone.

A control storm is simulated for approximately forty days using a modified version of the Advanced Hurricane WRF (AHW) model. The solution yields a storm in approximate statistically steady state that contains internal variability not complicated by external influences such as environmental flow that would otherwise not be separable from the effects of internal dynamics. The evolution and properties of these structures will be presented. Moreover, results from a predictable component analysis, and an ensemble sensitivity study, will also be summarized.

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